The present invention relates to a method for producing a component of a turbomachine, especially a hollow structural part of a turbine or a compressor. The invention also relates to a device for producing a component of a turbomachine, especially a hollow structural part of a turbine or a compressor.
Complex hollow, especially metallic or at least partially metallic, structural parts for high-temperature applications, such as, for example, high-pressure turbine blades are produced as a rule by means of precision casting with a directionally solidified or monocrystalline structure. The purpose of the directional solidification is avoiding grain boundaries which run perpendicular to the effective direction of the centrifugal force, because these adversely affect the creep behavior of the component. Monocrystalline structures do not have any grain boundaries at all and their creep properties are optimal as a result. However, the fineness of the hollow structure is limited by the casting process, the casting core and its distance. Thus, in casting technology according to the lost-wax method, for example, the production of the ceramic cores and the leachability thereof limit the fineness of the inner structures of the hollow structural part being produced and therefore the stiffness of the component as well as its cooling effect. For example, the enlargement of the inner surfaces, the formation of a grid structure to increase the stiffness and for improved heat exchange is no longer possible with current casting technologies without an increase in mass.
As a result, the object of the present invention is providing a method for producing a component of a turbomachine of the type cited at the outset, which makes the production of finely structured components, especially hollow structural parts of a turbine or a compressor, possible.
It is furthermore the object of the present invention to provide a device for producing a component of a turbomachine, which makes the production of finely structured components, especially hollow structure components of a turbine or a compressor, possible.
Advantageous embodiments with expedient further developments of the invention are disclosed in the respective dependent claims, wherein, where appropriate, advantageous embodiments of the method should be considered to be advantageous embodiments of the device and vice versa.
A method according to the invention for producing a component of a turbomachine, especially a hollow structural part of a turbine or a compressor, comprises the following steps: a) layer-by-layer deposition of at least one powder component material onto a component platform in the region of a buildup and joining zone, the deposition taking place in accordance with the layer information of the component to be produced; b) local layer-by-layer fusion or sintering of the component material by means of energy supplied in the region of the buildup and joining zone, wherein the environment of the buildup and joining zone is heated to a temperature just below the melting point of the component material; c) layer-by-layer lowering of the component platform by a predefined layer thickness; and d) repetition of steps a) to c) until the component is finished. By using a generative fabrication method, it is possible to produce finely structured components, especially hollow structural parts of a turbine or a compressor. In doing so, it is possible to produce components that can no longer be produced using casting technology such as, for example, structural parts having grid structures for increasing the structural strength with low dead weight and for considerably increasing the inner surfaces to improve cooling efficiency. In addition, it is possible by means of the generative construction method to incorporate boreholes directly into the structure for diverting the cooling air from the component. Because of heating the buildup and joining zone to a temperature just below the melting point of the component material, it is also possible to influence and control the crystal structure of the component being produced. In this case, especially a rapid prototyping method or rapid manufacturing method such as, for example, a laser beam deposition welding or an electron beam (EB) powder deposition welding is used as a generative fabrication method. The powder component material in this case may be made of metal, a metal alloy, ceramic, silicate or a mixture thereof. If the laser deposition welding is used as the generative fabrication method, then especially a CO2 laser, Nd:YAG laser, Yb-fiber laser or a diode laser may be used. Alternatively, an EB-beam may also be used.
In another advantageous embodiment of the method according to the invention, a first layer of the powder component material is applied in process step a) in such a way and solidified in process step b) in such a way that at least one directionally solidified or monocrystalline basic body of the component to be produced is formed on the component platform. However, it is also possible that, prior to the layer-by-layer deposition of the powder component material according to process step a), at least one directionally solidified or monocrystalline basic body of the component to be produced is applied on the component platform, wherein the contour of the basic body corresponds to the basic contour of the component in this component section. The basic body is a requirement for the design of a directionally solidified or monocrystalline component. These types of components have optimal creep properties. In particular, the additional layers of the powder component material deposited on the basic body in process step a) are applied in such a way that the directionally solidified or monocrystalline component is formed. The deposited additional layers grow epitaxially on the basic body and have the crystallographic orientation of the basic body. When depositing the powder component material, the growth of the component may be controlled by means of the parameters of laser output, feed rate, powder grain diameter and/or powder supply rate. In doing so, the process parameters conform to the component materials used.
In another advantageous embodiment of the method according to the invention, synchronously to the deposition or directly after the deposition of a layer of the component material, a laser ablation or EB removal of material protrusions is carried out to adapt the respective component section to a predetermined component contour in this region. Because of this process step, the degree of fineness of the structures is significantly improved once again because the excess material is removed with an ablation laser or EB-beam. In addition, there is the possibility that the cited removal, in particular the laser ablation, is carried out as a function of measurement data of the contours of the component in the respective component section recorded and processed by at least one optical measuring system. A short pulse laser in particular may be used for the laser ablation.
In another advantageous embodiment of the method according to the invention, the shape and material structure of the component is determined as a computer-generated model and the layer information generated therefrom is used to control at least one powder feed, the component platform, at least one deposition laser or at least one electron beam (EB) powder deposition device. As a result, automated and computer-controlled production processes are possible.
In other advantageous embodiments of the method according to the invention, the heating of the buildup and joining zone to a temperature just below the melting point of the component material is carried out in a high temperature zone of a zone furnace. The zone furnace is especially advantageous in the production of components with directionally solidified or monocrystalline crystal structure, because the zone furnace makes it possible to maintain a predetermined temperature gradient perpendicular to the solidification front. To this end, in particular the component to be produced may be moved from the high temperature zone of the zone furnace by means of the component platform to at least one zone having a lower temperature.
A device according to the invention for producing a component of a turbomachine, especially a hollow structural part of a turbine or a compressor, comprises at least one powder feed for depositing at least one powder component material on a component platform in the region of a buildup and joining zone, means for heating the buildup and joining zone to a temperature just below the melting point of the component material as well as at least one radiation source for a local layer-by-layer fusion or sintering of the component material by means of energy supplied in the region of the buildup and joining zone. The device according to the invention makes the production of finely structured components possible, especially of hollow structural parts of a turbine or a compressor of a turbomachine. This is caused in particular in that the device for carrying out a generative fabrication method, such as, for example, a rapid prototyping method or rapid manufacturing method, in particular a laser beam deposition welding, an electron beam (EB) powder deposition welding or deposit welding is aligned with wire. In contrast to known casting methods, much smaller and finely formed structures may be produced. By heating the buildup and joining zone to a temperature just below the melting point of the component material it is also possible to influence and control the crystal structure of the component being produced. A laser or an electron beam device may be provided as a radiation source for the input of energy in the buildup and joining zone. In the case of the use of a laser, in particular a CO2 laser, Nd:YAG laser, Yb-fiber laser or a diode laser may be used. The powder component material may in turn be made of metal, a metal alloy, ceramic, silicate or a mixture thereof.
In another advantageous embodiment of the device according to the invention, the powder feed or deposit welding with wire is arranged coaxially or laterally to the radiation source. As a result, the device may be adapted in an optimal manner to the space available for the respective task.
In another advantageous embodiment of the device according to the invention, the means for heating the buildup and joining zone comprise a zone furnace. By using a zone furnace, a predetermined temperature gradient may be maintained perpendicular to the solidification front of the growing component so that, for example, components with a directionally solidified or monocrystalline crystal structure may be produced.
In another advantageous embodiment of the device according to the invention, the means for heating the buildup and joining zone are designed to be at least partially evacuable or floodable with an inert gas. This permits the welding quality to be improved substantially.
In other advantageous embodiments of the device according to the invention, the device comprises at least one ablation laser for a laser ablation of material protrusions to adapt a component section to a predetermined component contour. To this end, the ablation laser may be coupled with at least one optical measuring system. The laser ablation is carried out as a function of measurement data of the contours of the component in the respective component section recorded and processed by the optical measuring system. By comparing the measured contours to a predetermined final contour, it is possible to correspondingly control the ablation laser so that excess material is removed from the component. This makes a further improvement in the quality of the fine structures of the component possible. A short pulse laser is normally used as the ablation laser. However, it is also conceivable for the removal of excess material to be carried with the electron beam.
The method according to the invention described in the foregoing and the device according to the invention likewise described in the foregoing is used for producing engine components made of nickel-based or titanium-based alloys, especially for producing compressor blades or turbine blades.